If UNDERdrive pulleys are so great, why aren't they factory/OEM?

[Bob Ayers]

I don't know about headers. The heads on my wife's Honda Pilot have a huge oval exhaust pipe coming straight out of them. There is no 3 into 1 manifold or header. All the secret shit is done in the cylinder head--which is huge. It moves enough air to make 255hp out of 3.5 liters at only 5,750rpm. I think the stereotypes we grew up with can be safely shitcanned.

Honda get's great low end to high end performance from VVT (Variable Valve Timing), which they call VTEC.

 

[Bob Ayers]

Many vehicles come with headers from the factory, including Rangers.

Which Ranger comes from the factory with headers?

 

[Mutant Pony]

Some 2.8, 2.3 , 2.5 and 5.0 fords had tubular exhaust manifolds. Some people call them headers because they are similar in construction.

 

[exbass94]

My buddy's 1998 2.5 Ranger has a stock header on it. And I agree about how the factory compromises the tuning/performance so the vehicle can operate well under various conditions. It's the same reason they have the programmers for the truck's computer. The stock computer tuning is a compromise too, and the programmer allows you to tune it for your specific purposes and get more power in the areas you want.

 

[krugford]

One of the largest tradeoff's is emissions. Unfortunately, it's the one that is least considered when performing aftermarket modifications.

 

[mountaineergreen]

The underdrive pulleys do serve a purpose. They are not for everyone as has been stated, but for some people, they are ideal. Ford has to make these trucks capable from the factory for virtually every climate area, from the northern states to the heat of the south. Grandma drives them, contractors use them for loads beyond their stated capacity. Grandma wants the steering to be easy, contractors want them to tow heavy loads and idle for hours on end without overheating. They have to be able to drive in the heat of the desert, with heavy electrical loads, some models came with larger tires, etc. The system is designed with every contingency in mind to fit a wide range of uses.

For what I use my Ranger for, they are perfect. I use my truck for daily driving and light towing only. I installed the alternator overdrive pulley to bring the alternator speed back to stock. I have noticed no ill effects when turning even at idle when stopped, the A/C still blows cold, the temperature gauge has never moved above where it sat before. I gained 2-3 MPG from the pulleys which I spent $120 on. Its a no brainier at $4 a gallon plus. If i were towing heavy loads, using the truck for delivery service or other things like that, they wouldn't be useful. I'd wager the average drive would never know the difference if they were installed except for increased economy and power.

 

[Bob Ayers]

One of the largest tradeoff's is emissions. Unfortunately, it's the one that is least considered when performing aftermarket modifications.

Emissions are not considered when the PCM goes open loop at WOT.

 

[red2003xlt]

One thing forgotten when discussing factory vs. aftermarket.

Production cost; cast iron exhaust manifold are dirt cheap to make.
Tubular headers are labor intensive and not worth the return for low performance vehicle.

 

[fixizin]

Another thing, why do these simple pulleys--which will never see even 6,000 RPM--cost well north of $100????

 

[krugford]

Emissions are not considered when the PCM goes open loop at WOT.

Engines have to pass emissions at a wide variety of operating points. There are least two points on the full load curve that watched closely during engine developement, rated speed and peak torque speed. Just because the computer is in open loop doesn't mean emissions go out the door.

 

[Bob Ayers]

Engines have to pass emissions at a wide variety of operating points. There are least two points on the full load curve that watched closely during engine developement, rated speed and peak torque speed. Just because the computer is in open loop doesn't mean emissions go out the door.

Sorry, EPA emission standards are exempt at WOT!!!

 

[krugford]

Can you provide a source to back that up? When I'm developing an engine model, those two points are the first two points I calibrate to, for many reasons, and the two I watch the closest during performance testing. Could we be talking about application differences here?

 

[fixizin]

Except in its under-reported top-fuel funny car application, the humble Ranger engine spends how much time at WOT?

 

[Bob Ayers]

Can you provide a source to back that up? When I'm developing an engine model, those two points are the first two points I calibrate to, for many reasons, and the two I watch the closest during performance testing. Could we be talking about application differences here?

Google "WOT emissions", "emissions at WOT", "EPA emission standards", .....etc.

and you will find a ton of information about no emission standards at WOT.

Bottom line, no EPA emission standards at WOT.

 

[krugford]

Thanks for telling me how to find information on Google Bob, but I haven't found anything that specifically states an exemption at WOT. I've found the required driving tests (FTP75 - Cold, Transient, and Hot Start) as well as the supplemental tests for agressive driving (US06 SFTP) and air conditioning (SC03 SFTP). All of these tests feature acceleration and decelerations over a given amount of time with some steady state operation in between. I would think that for some vehicles, there may be points when they are operating at WOT, which would contribute to the composite emissions score for the duration of the test.

My background is in Off-highway applications, which do require testing at WOT, and don't really apply here. But my common sense is telling me that there's no reason to exclude the entire full load curve for light duty on-highway applications.

As for my original statement that sparked the comment on emissions in the first place, I find it to be true. Emissions is the biggest loser when it comes to the aftermarket power/fuel economy tradeoff. IMO, it's also one of the biggest reasons that cars are getting more sophisticated while gas mileage is staying the same or dropping. Tighter emissions controls require more fuel because in the long run, all you're doing is trading the more harmful emissions (PM, NOx) for the less harmful ones (CO2).